As a conventional air-conditioning apparatus in, such as, a multi-air-conditioning apparatus for buildings, there is an air-conditioning apparatus that causes a refrigerant to circulate from an outdoor unit to a heat medium relay unit (relay unit) and that causes a heat medium such as water to circulate from the heat medium relay unit to indoor units, so as to reduce the power used to convey the heat medium while causing the heat medium to circulate to the indoor units (for example, Patent Literature 1).
Further, as a conventional air-conditioning apparatus that uses a non-azeotropic refrigerant mixture, there is a chiller-type air-conditioning apparatus that causes a non-azeotropic refrigerant mixture and a heat medium to flow through a heat exchanger related to heat medium (refrigerant/heat medium heat exchanger) in opposite directions (that is, the flows are in counter flow relative to one another) to improve heat exchange efficiency (for example, Patent Literature 2).
Further, as a conventional air-conditioning apparatus that uses a non-azeotropic refrigerant mixture, there is a chiller-type air-conditioning apparatus that causes a non-azeotropic refrigerant mixture and a heat medium to flow through a heat exchanger related to heat medium serving as an evaporator of a refrigerant circuit in parallel in the same direction (that is, the flows are parallel flows) to prevent freezing of the heat medium while keeping the temperature of the heat medium at the inlet of the heat exchanger related to heat medium constant (for example, Patent Literature 3).